1. Field of the Invention
This invention is directed to a method and apparatus for dispensing product from a product containing bag. In particular, the present invention is directed to a unique method and apparatus in which a product containing bag and a pressure regulating system are disposed in a dispenser where the pressure regulating system is activated by the filling of product into the bag.
2. Related Art
In recent years various efforts have been exerted to supplant conventional aerosol-type dispensers, which use or used hydrocarbons such as isobutane, or fluorocarbons such as FREON refrigerant manufactured by DuPont, or other propellant means. Moreover, environmental concerns, including protection of the earth's ozone layer have placed limitations on usage of such conventional aerosol-type dispensers. These concerns and a variety of other considerations, including cost, wasted product and flammability, have prompted considerable research and development activity aimed at finding alternative means to dispense various flowable material products.
It is known to provide a product dispenser which uses a product containing bag disposed in a container and to provide a pressure generation mechanism in the container exterior to the bag to apply a pressure to the bag. A dispensing pressure is thus defined by the pressure generation mechanism.
It is also known to provide a pressure maintenance system within an enclosure or bag in which the dispensing pressure is produced. In these systems the product is exterior to the pressure generating bag.
Both of these systems have drawbacks. The product containing bag arrangements do not have controlled pressure regulation by which an initial dispensing pressure is substantially regenerated in the container upon dispensing of product unless liquefied gases are used. The pressure generating bags have drawbacks in the efficiency of product dispensing, i.e. the amount of product that is not dispensed because it is trapped in the container by the pressure generating bag. Both systems also have the drawback of requiring extra steps to activate the dispenser to provide an initial dispensing pressure. Additionally, there is a problem in setting the dispensing pressure at a desired initial pressure. Furthermore, in the pressure maintenance systems, while in gross terms the periodic release of a reactant into the second reactant maintains a pressure in the pressure generating bag, the dispensing pressure in that bag, if measured over time, shows a plurality of peaks and valleys. Thus, the pressure is not always regulated to a substantially constant pressure value during the dispensing process.